The present invention relates to a multi-usable thermal transfer ink sheet. More particularly, it relates to a multi-usable thermal transfer ink sheet designed so that a homogeneous heat-meltable ink layer is transferred in increments relative to the thickness thereof onto a receiving medium at every time when the ink layer is heated by means of a heating means such as a thermal head.
This type of thermal transfer ink sheet which has been proposed heretofore includes one having a multi-transferable, heat-meltable ink layer containing 30 to 60 parts by weight of a heat-meltable resin, 10 to 40 parts by weight of a heat-meltable substance such as wax and 30 to 60 parts by weight of a coloring agent as the essential ingredients (see JP,A, 2-277691).
There have been also proposed those wherein, in the above-mentioned multi-transferable ink layer, the content or melt viscosity of the heat-meltable resin is increased on the side of the foundation and decreased on the side of the surface of the ink layer (see JP,A, 61-79695 and JP,A, 2-150385).
However, these conventional multi-usable transfer ink sheets are not satisfactory because they have drawbacks such as poor clearness of images obtained, particularly, on a paper having a poor smoothness (hereinafter referred to as "rough paper") and occurrence of a remarkable "receiving paper-staining" which means the phenomenon that portions of a receiving paper where the formation of images is not desired are stained with the ink.
It is an object of the present invention to provide a multi-usable thermal transfer ink sheet which can form clear images even on a rough paper and causes no receiving paper-staining, with ensuring a desired multi-printing property.
This and other objects of the present invention will become apparent from the description hereinafter.